1. Field of the Invention
The present invention relates to a storage system for storing data and, in particular, to a management technique for a storage system including a plurality of storage apparatuses adopting a redundancy configuration.
2. Description of Related Art
Data stored in a storage apparatus is usually backed up in another storage apparatus, which is a redundant storage apparatus, to prevent data loss due to failures in disk drives in the storage apparatuses. An exemplary backup technique is called ‘remote copy.’ With the remote copy technique, data is managed so that data is synchronously or asynchronously copied between a primary storage apparatus and a physically-separate storage apparatus, with the two apparatuses being defined as a pair. As a result, data consistency between the storage apparatuses is ensured, and even if a failure occurs in the primary storage apparatus, the stand-by storage apparatus can take over receiving I/O access from the host computer from the primary storage apparatus.
JP2006-309447 A discloses a technique where a first storage apparatus stores data sent from a host system and transfers the stored data to second and third storage apparatuses so that the second and third storage apparatuses each store the transferred data. In addition, the second and third storage apparatuses mutually verify the data they store.
In a storage system utilizing the remote copy technique, when a failure occurs in one of storage apparatuses, a different standby storage apparatus takes over receiving I/O access from the host computer targeting the faulty storage apparatus from the faulty storage apparatus, thereby allowing the host computer to continue I/O access with the standby storage apparatus.
However, because no redundant storage apparatus is left after the standby storage apparatus has taken over receiving I/O access, the redundancy configuration has to be reestablished as soon as possible. Conventionally, a system administrator has to reestablish the redundancy configuration, which is an extremely complicated task, using his/her experience alone.